This invention relates generally to electrical circuits for discriminating between noise and a desired electrical signal. More particularly, this invention is directed to an electrical circuit for receiving a train of data pulses and any accompanying noise pulses and for identifying a first incoming pulse as either a noise pulse or the beginning of a train of data pulses.
In information systems which operate on trains of data pulses, i.e., data "characters," such characters may be in the form of a series of pulses preceded by a "start" pulse and followed by one or more "stop" pulses. Each character may thus be operated on as a unit since the start and finish of each character is clearly identified by the presence of start and stop pulses. However, when noise pulses accompany the data characters, the system may mistakenly identify a noise pulse as a start pulse. Such mistaken identification of a noise pulse as a start pulse may undesirably open a data processing channel to the reception of further noise pulses rather than maintain the data processing channel in a closed condition as it would be if the noise pulse had been correctly identified as noise.